hall sensors to sensorless motor

[mr watts]

Hi,all, I have a geared hub motor originally with speed sensor (now disconnected) and I am running it as sensorless with a dual mode controller.
It seems to judder a lot,and the question is can I add hall sensors between the stator slots rather than buried into them?
Does anyone have any links to tutorials for this?
Any advice appreciated

 

[vfr400]

If it had sensors before, the replacements have to go in the same position. If you didn't have them before, the positioning is critical. They set the timing of each phase pulse.